Viconics R842 User Manual

R842 Electronic Relay For Electric Baseboards

Description

Viconics’ innovative R842 electronic relay has been
designed for silent control of high voltage resistive
heater loads (120V to 600 Vac) from a low voltage
control circuit. Typical applications include control of
electric baseboard and cabinet heaters in commercial
buildings. Inductive motor loads can also be controlled
(120 and 240 Vac models only).

Using advanced microprocessor-based circuitry, the
R842 is capable of handling greater than 500,000 cycles
(typical). It has a built-in transformer and is compatible
with most industry standard electromechanical or
electronic thermostats with on/off outputs. A unique
feature of product is that it can operate with a value
priced Viconics’ T186 electronic PI (proportional and
integral) room thermostat with setpoint capability,
providing exceptional accuracy, comfort, and energy
savings.

Features Benefits

• Built-in transformer

• Universal replacement part

• Compatible with electronic T186 room sensor

Fig.1 - R842 relay for electric baseboards

⇒ Permits fully electronic PI control

• Unique compatibility with Viconics’ own designer

electronic thermostat

⇒ Improved accuracy (+/-0.3ºC) and comfort
⇒ Energy savings
⇒ Aesthetically pleasing thermostat

• Reliable microprocessor-based design ⇒ Long life

• Compatible with all standard 24 V thermostats ⇒ Adds flexibility

• Constant 10 second time delay

• Built-in transformer

• Broad voltage ranges available: 120, 208, 240,

⇒ Not affected by ambient temperatures typically

found in older, thermal type baseboard relays

⇒ Less inventory to stock
⇒ Easier installation
⇒ Covers most voltage applications

277, 347, 600 Vac.

• Status LED

⇒ Confirms operation
⇒ Simplifies troubleshooting

• Silent operation ⇒ Will not disturb occupants

• Direct replacement of competitive models ⇒ Easy to retrofit

• Large resistive amperage load rating ⇒ Will handle the largest baseboards with ease

• Inductive ratings ⇒ Used to control motor loads (fans, pumps, etc)

• Compact enclosure ⇒ Fits inside baseboard

• Standard ½” male conduit bushing ⇒ Can be installed on most electrical junction boxes

• 2 year warranty ⇒ Assured dependability

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Description (Cont’d)

(

)

The R842 has several advantages over traditional
electromechanical baseboard relays. The latter use
the principle of thermal expansion to make or break
the high voltage circuit. This operation typically takes
45 seconds and adds inaccuracy to the temperature
control loop. The R842, with enhanced electronic
circuitry, substantially reduces this long time delay
and is not affected by ambient temperature
conditions.

Due to its compact design, the R842 easily fits into
most electric baseboard enclosures and can replace
most competitive models. For junction box mounting,
a standard ½” male screwed fitting is available. In
addition, a high intensity LED is provided to indicate
operation and simplify troubleshooting. Silent
operation will ensure that each installation is trouble
free.

R842 Relay Models

Model No.

R842-120
R842-208
R842-240
R842-277
R842-347
R842-600

Voltage

Vac)

120 22
208 22
240 22
277 19
347 18
600 10

Amperage

(A

T186 Electronic PI Thermostat

The microprocessor-based design of the R842
permits the use of T186 electronic room sensor with
setpoint as an alternative to electromechanical
thermostats. The T186 transmits the actual
temperature and setpoint to the R842. The resulting
solid state PI control loop is much more accurate
than that offered by conventional thermostats and
eliminates wasted energy caused by on/off cycling
with these types of thermostats (see Fig. 2).

The T186 can also be used as lower cost alternative
to the use of solid state relays and pulse width
modulated thermostats, sometimes used to control
electric heat baseboards.

Electromechanical thermostat

Temperature

T186 PI control

Setpoint (comfort temperature)

Fig.2 - On/Off mechanical control vs PI electronic control

Time

T186 Sensor Models

Model No. Scale Range

T186C-01
T186F-01

5 °C to 30 °C

40 °F to 90 °F

Fig.3 - T186 electronic PI room sensor with setpoint

Typical Guide Specification

The relay shall be a microcomputer-based with PI, time
proportioning control capability. It should have an
average life of greater than 500,000 cycles and include
a built-in transformer. Relays shall be compatible with
all of the following control signals: Viconics T186
electronic room sensor with setpoint permitting PI
control with an accuracy of +/-0.3ºC and standard 24
Vac thermostats. Relay shall have a constant 10 second
time delay and shall not be affected by ambient
temperatures. The relays shall be equipped with a
status LED to confirm operation. Required quality: R842
electronic baseboard relay from Viconics.

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